This invention relates to the recovery of thermoplastic that has been manufactured into plastic piping. In one of its aspects, this invention relates to reducing thick-walled, large diameter plastic piping into a continuous, thermoplastic ribbon. In another of its aspects, this invention relates to relieving the plastic memory from an elongated piece of thermoplastic. In another of its aspects, this invention relates to the comminution of thermoplastic piping.
It is well known to extrude thermoplastic piping that has the internal diameter of 48 inches or more which has side walls of thicknesses as great as 11/2 or 2 inches. As in every manufacturing process, in the natural course of events, sufficient scrap and off-specification, extruded piping is produced to warrant a recovery of the thermoplastic for reprocessing. Unfortunately, because side walls are progressively thickened as the diameter of the extruded pipe is increased, thermoplastic piping having a diameter greater than 6 inches becomes progressively more difficult to reprocess to the granular form necessary for proper mixing and reworking as an extruder feed.
Some of the presently used methods for preparing larger diameter pipe for reprocessing require excessive amounts of manual labor in crosscutting and re-crosscutting sections of piping until pieces small enough to be easily handled by the normal comminuting equipment are attained.
It is therefore an object of this invention to provide a process for preparing thermoplastic piping for reprocessing. It is another object of this invention to provide a combination of equipment for preparing thermoplastic piping for reprocessing. It is another object of this invention to provide method and apparatus for obtaining from thick-walled large diameter thermoplastic piping pieces of thermoplastic of sufficiently small size as to be easily processed in an extruder.
Other aspects, objects, and the various advantages of this invention will become apparent upon studying this disclosure, the drawing, and the appended claims.